Given the fact that the "ass-engined Nazi slot car" has followed the flat-six-way-out-back format since Day One--with each iteration a significant improvement over the last despite each years' engineering headaches--shows not only how great that original design was, but also how far it can be pushed ad infinitum.

Seconded, wholeheartedly! Porsche has all but perfected the art of the flat-six. It has become as iconic as the shape of the 911 itself, and integral to the overall car. Seriously, is a 911 a 911 WITHOUT a horizontally-opposed six-cylinder engine?